1. Technical Field
The inventions relate to audio signal processing, and in particular, to spectral refinement of audio signals in communication systems.
2. Related Art
Background noise may distort the quality of an audio signal. Background noise may affect the intelligibility of a conversation on a hands-free device, a cellular phone, or other communication device. Audio signal processing, such as noise reduction and echo compensation, may improve intelligibility through a spectral subtraction. This method may dampen stationary noise and may require a positive signal-to-noise distance. Spectral subtraction may distort speech when spectral noise components are damped and not eliminated.
Audio signal processing may divide an audio signal into overlapping sub-bands. The sub-bands may be transformed into the frequency domain and multiplied by a window function. The frequency response of a window function may cause the sub-bands to overlap. The overlap may decrease noise damping in frequency ranges adjacent to the desired signals. When the discrete resolution is increased to reduce sub-band overlap, the modified resolution may decrease the time resolution of the processed signal. This process may cause undesirable and unacceptable time delays.